MRI-PET , FUSION IMAGING, DIFFERENT SPIN UNDER THE RIM.

1. PET-MRI
HYBRID IMAGING
A different spin from under the rim
DR. MITUSHA VERMA
DEPT. OF RADIODIAGNOSIS
DR.B.NANAVATI HOSPITAL
MUMBAI.

2. A NEW PAGE ADDED TO HISTORY OF
IMAGING….
 PET / MRI approved by FDA in June 2011.
In these two years,
 The technology continue to struggle with learning
how to integrate the system with workflow.
 Comparing the utility of PET/MRI versus PET/CT.
 Determining which organs and disease
processes are best imaged with PET/MRI

3. PRINCIPLE OF PET: Coincidence Detection

4. Structural
MRI
Functional
MRI
PET MRI
Metabolic
PET
Perfusion
Spectroscop
y
Dynamic
MR
CONCEPT OF MRI-PET

5. Excellent human anatomical information.
Superior soft tissue characterization.
Better temporal resolution.
Less Radiation Hazards.
HIGHLIGHTS OF MRI-PET

6. TYPES OF SCANNERS
 Simultaneous Scanners  Sequential Scanners

7. CHALENGES IN IMPLEMENTATION
 PET detector element related issues.
 Attenuation correction related issue.
 System Correction.

8. PET DETECTOR ELEMENT RELATED ISSUES
 Strategies to limit the interference of the magnetic field of the
MRI scanner, with the detection of the PET signal
 In terms of the ideal detector crystal, Lutetium
oxyorthosilicate (LSO) and Bismuth germinate (BGO) have -
least susceptible to MR artifacts.
 Using optical fibers that guide light away from the magnetic
field
 Replacing the PMT with avalanche photodiode devices
(APDs)
 Shielding the PMT from the surrounding magnetic field

9. INDICATIONS FOR MRI-PET
 Neurology – Dementia
Epilepsy
Stroke Imaging
 Oncology - Brain Tumours
Pelvic Tumours
Head and Neck Tumours
Lymphoma
Sarcoma
Langerhans cell histiocytosis
Breast Cancers
 Pediatric Imaging.
 Cardiac Imaging.
 Musculoskeletal Imaging.

10. 75- year old female, presented with left breast lump. FNAC from
the lump showed atypical cells.
Dynamic post contrast axial MIP image
Spiculated mass with intense FDG uptake.
FDG non avid small nodular enhancing lesion detected
in the right breast detected on MR I

11. FDG avid metabolically active marrow lesion in the left
pubic bone: definitive osseous metastasis

14. 44 year old male, known case of left temporal low grade Glioma
operated upon 6 years back with post-operative RT has now
presented with suspected recurrence.
Simultaneous PET MRI provided information regarding FDG uptake, rCBV, rCBF, Choline/Creatine
and Choline/ NAA ratio from each tissue element at the same time, making a diagnosis of
recurrence accurately that subsequently proved on histology following resurgery.

15. REVIEW OF LITERATURE…..

16. “With PET/CT, we’ve been able to localize things. Now
we can give more precise location with MRI than with
CT. MRI has the capability of doing functional imaging,
combined with physiology-based imaging of PET.
We’ve doubled the amount of things we can see with
this.”
“Since MRI provides more biological and functional
data than CT — without radiation —the system is a
huge advantage for pediatric patients and those
needing multiple scans”

17. If a tumor is shown to be metabolically active via PET, but shows poor
tissue perfusion, does this have management implications for
chemotherapeutic regimens? Should a physician change the chemo
treatment if the patient has a cancer without enough blood flow?
Another topic is lymphoma treatment. MRI is good at detecting bone
marrow edema, which indicates that lymphoma is spreading to the
bones. Patients with lymphoma often receive PET scans as well as
bone marrow biopsies. Can a PET/MRI offering information about
marrow edema replace a painful biopsy?

18. Macromolecular information (in micromolar quantities
through MR spectroscopy, perfusion imaging, cell
migration imaging, with iron labeling and oxygen
consumption imaging, with 17O among others) can
now be combined with the picomolar detail that
metabolic imaging with PET provides.

19. “We don’t think (PET/MRI) will replace PET/CT
for older adults who have cancers easily worked
up by PET/CT, but selected applications like
pediatric malignancies, pelvic malignancies, head
and neck cancer, those areas are going to be
extremely exciting.”

20. THANK YOU….